Automatic switching equipment



May 28, 1929. R. E. BEAR 1,714,938

AUTOMATIC SWITCHING EQUIPMENT Filed April 28, 1928 Inventor: RalstonE.Bear, WWW

Hus Attorney Patented May 28, 1929.

UNITED STATES PATENT OFFICE.

'RALSTON E. BEAR, or LOS ANGELES, CALIFORNIA, AssIGNoR T GENERALELECTRIC I comm, 1 conreorm'rron or raw YORK.

AU.!'OIA TIC SWITCHING EQUIPMENT.

Application filed April 28,1928. serial to. 273,780.

My invention relates to automatic switching equipments and particularlyto automatic switching equipments for controlling the connection betweena plurality ofsources of current and a plurality of load circuits sothat under light load conditions all of the load circuits are suppliedbL' the same source and under heavy load con itions certain of thecircuits are independently supplied by different sources and one objectof my inven- 'tion is to provide an improved control varrangement foraccomplishing this result.

In accordance with my invention I pro vide an arrangement whereby aplurality of load circuits are normally supplied by a preferred sourceof current and an auxiliary source which is arranged to supply certainof the load circuits when the preierred source if overloaded is normallyinoperative. WVhen the load on the preferred source reaches apredetermined Value which indicates that the load is approaching avalueat which it is dc.- sirable to place the auxiliary source in service, the auxiliary source is startedand placed 7 in an operativecondition to supply current.

\Vhen the load on the preferredsource 'exceeds another predeterminedvalue certain of the load circuits are disconnected from the preferredsource and are connected toithe auxiliary source. Suitable switchingmeans is provided whereby either source may be made the preferred sourceand the other the auxiliary source.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing which diagrammaticallyshows a-control system for controlling the connection between two loadcircuits and two sources of current and the scope of my invention willbe pointed out in the appended claims.

In the accompanying drawing 1 and 2 are two load circuits which arearranged to be connected to a main bus 3 by switches 4 and 5. The loadcircuit 1 is also arranged to be connected to an auxiliarybus 6 byaswitch 7. The switches 4, 5 and .7 may be of any suitable type examplesof which are well known in the art. JFor supplying current to themainbus 3 and the auxiliary bus '6 I provide two sourcesofcurrentwhichmiry be of any suitable type. As shown these sources arethe generators 8 "circuit 14. The motors 12 and 13 are pro vided withsuitable automatic switching means respectively whereby the starting ofeach motor generator set is vefi'ected by the completion of a startingcircuit associated therewith. Since such automatic switching systemsare-old and well known in theart and the details thereof constitute nopart of my present invention, I have deemed it unnecessary to complicatethe drawing by showing these switching means in detail.

The automatic switching means 15 .(not

shown in detail) for the motor 12 is arranged to be operated to effectthe starting of the motor 12 whenever a starting circuit 16assoelatedtherewith is completed. The auto matic switching means 17 (not shown indetail) associated with the motor 13 is similarly arranged tobe operatedto effect the Starting of the motor 13 whenever a starting circuit 18associated therewith is completed. Manually controlled switches 19 and20 are shown as one particular arrangemcnt'for ef- 'fect-ing at will thecompletion of thestarting circuits 16 and 18 respectively. Any othersuitable control means, however, examples of which are'wellknown in'theart may beprO- vided for accomplishing this result;

For exciting the generators 8 and 9 I providethe exciters '22 and 23which are directly connected to the motors 12 and 13 respectively andwhich are arranged to be connected to the field windings of thegenerators 8 and 9 respectively by suitable field switches 2i and 25.These switches 24 and 25 may be controlled either automatically ormanually in any suitable manner examples of which are well known in theart.

In order that either generator may be made the preferred source and theother the auxiliary source I provide a transfer switch 27 which isarranged when in one position to connect the generator 8 to the main bus3 and the generator '9 to the auxiliary bus 6 and which is arranged whenin another position to connect the generator 9 to the main bus 3 and thegenera-tor 8 to the auxiliary bus 6.

Under light load conditions both of the switches 4 and 5 are closed sovthat the load '1 loadedi.

source is connected thereto.

circuits 1 and 2 are connected to the main bus sponsiveto the voltage ofthe bus .3 anda voltage relay 29 which is'connecte'd to the loadc-1rcu1t'2 so as to be responsive to the voltage thereof. hen them-ambus 3 is energized and the load circuit 2 is deenergized and enerlliarysource. In order that this relay. may

gi'zing circuit is completed through the contacts of the relays 28 and29 for acontrol relay30 across a suitable-source of control current 31.In the arrangement shown in the drawing the control circuits 31 isarranged to be connected by. means of a manually controlled switch 32 tothe' secondary ofa potential transformer 83, the primary of which isconnected to the supply circuit 1 1. {The con.- trol relay 3Owhenienergized completes acir-v cuit fol-the closing coil 34,01? the:switch across the control circuit 31 so that the switch pletesi alocking circuit for. the control relay so. that the opening orthecontacts of the voltage relay 29 due to the energization of the loadcircuit 2. does not effect {the 'deenergization of thecontrol relay 30.1 Y

i The closingof the switch 4; between the mainibus. 3 d ad circuit 1is-conttollfid by the-Voltage y s which is responsive to'fthe voltage ofthe bus 3 and also by a voltage 1Gl&yf86\Vl1lCl1:lS connected across theload circuit 1 so that it'is responsive to the voltage thereoffl Whenthe main, bus 3 is energized andtheload circuit 1: is deenergized acircuit is completed "for the control .relay'37through'the contacts ofthe relays 28' and 36. l/Vhen the relay 37 is "energized lit completes acircuitfor the closing c'oil 38of the switch 41 if'the switch 7 isopenand either of the ficldiswitches 24: or 25 is -open indicating that:both generators are not'excited or the current output :ofthesourceconnected to themain bus 3 is below'a predetermined value,

thereby indicating that the sourceis notover- In accordance withonefeature of iny invent-loathe auxiliary motor. generator set snormally shut down so that it is man 1noperative condition to supplycurrent to the aux.-

iliary bus andis arranged who started automatically and to be placed inan operative condition to supply current to the auxiliary ;,bus' whenthe current output ofth'e source connected to the mainbus-reaches apredeftermin'ed Nalue. lVhenjthje current outputot the source connectedto .themainubus reaches is; accom' lished} in 1 the followin =manner.

Tworelays 40 and} -11 are connected to the Thee nergiZatiOn of therelay'5 is'closed. 1 The switch 5 when closed COIl'I-i main bus 3 in anysuitable manner so that they are energized in accordance with thecurrent output of the source connected (to the main bus. When the"current output of the source connected to the main bus reaches apredetermined Value the may ato opcrates and completes the. circuit 01 acontrol relay 4&2 associated therewith. This control relay inturncomp-letes the startingcircuit or the automatic. switching meansassociated with whichever motor generator set .is, the auxcompletethe'proper starting circuit'the transfer switch 27 is providcd withsuitable I contacts 7 sojthatin each operative position of the switchthe/"contacts of the-relay 42 are connected across the startingcircuitjof'which-' ever source isthe auxiliary source.

If the output of the source conneeted'to'the main-bus exceeds a' greaterpredetermined value: the ;relay "4:l completes the circuit of anauxiliary f relay 43 associated therewithopening or the switch 4; so asto'd'isconne ct the load circuit 1 from the mainb'us The energization ofthe relay ialso' completes acira predetermined a'lu'efso that thevoltage relay lfi, which isconnected'across the aun I iliary bus 6, isenergized a predetermined effects the 2 amount. As soon as the controlrelay'ee becomes energized and the switch 4 is opened a circuitiscompleted for the-closing coil 46 of the switch 7to close the switch 7and connect the load circuit '1 to the auxiliary bus 6. r The circuit ofthe closing'coil 16 includes the manually controlled S'Wlt't'h' lj?whichjis provlded so thatthe switch 7 maybe opened to effectthcdisconnection ot the loadcircu-it V l'from' the auxiliary bus 6 anditsueconnecs on the two load'circuits is such that it :may

(the operation 1 ;tion' to Ithe main bus "3' when the total load 1 s 1 J'110 the arrangement shown in theaccompanyingdrawing is as follows: E

Let-it: be assumed-that the switches 24-, 25,

32 and'lL'TQ-are closed and that the transfer switch 27 is in itslefth'andposition so that the generator 9 is connected :to the auxlhary bushand the generator Sis connected to the mainbus 3. hen it .is dcsired tosupply.

currentito the load circuitsl and 2 from the main source 8 themanuallycontrolled switch 19 is closed so as to "effectthe completion of thestarting circuit 16 1 and the operation. of the automaticfswitch ngmeansfle associated with the motor-12 to' start the motor genera 1'tor'set 10. As soon as the voltage of the 'erator' 8 builds up toa'predetermmedwalue" the voltage relay 2S1operates-t0; closeits contacts51- o frthe voltagerelay, 29 willbe closed tactsfit). If at thistime'the load circuit 2 is i not; energizedby some ,other-soiirceth'e=con- Y 7 V by closing itscontacts 53 connects the closing coil34 of theswitch 5 acrossthe control circuit 31 so that theload circuit 2 isconnected to the main bus 3. By closing its auxiliary contacts 54 thecircuit breaker 5 completes r a locking circuit for therelay 30 so thatthis relay is not deenergized by the opening of thecontacts 51 of therelay 29 when the load circuit-2 energized, v

If the load circuit 1 is not, energized by lsomerot her source at thetime the relay 28 closes its contacts 50 a circuitis completed for thecontrol relay 37, This circuit is from one side of the control circuit.31 through the coil of relay 37, r esistor 55, contacts 5.6 of relay36, contacts 50 ofrelay 28 to the other side of the control-circuit.Relay 37'byclosing its Contacts 57 completes a circuit for theclosingcoil 38 0f the switch 4. This circuit is from -.one side of thecontrol circuit 81 through swit cli 47, closing coil 38 of switch 4, theparallel connected contacts 58 59 and 60 of relay .43and field switches24 and respectively, contacts 57 of relay 87, auxiliary contacts'fil onswitch 7 to the other side of .31 throughswitch 47 a n; "creativeL onidthe control circuit. The energization of the closing coil38 closes theswitch 4 so that the load circuit 1 is connected to the main bus 3.

contacts 62 of relayj'40 to the other side of the control circuit 31';The relay 42 by closing its contacts 673 completes a circuit in parallelaround thecontacts 62 of relay 40 so that the relay 42 remains energizedin case the relay 40 subsequently opens its contacts .42, Relay 42 byclosing its contacts 64wl1iclrare con: nected in the starting circuitbythe means of V the transfer switch 27' effects the operation of theautomatic switchingv means 17- assoelated with the motor 13 of the motorgeneratorset ll/ The automatic switching means 17 thenefliects thestarting of the motor gen,- lator S '1fiefl ha thf g nera r i pl c 1 Ion to supply current it l when the switch is sub} to 1 'ad ci' cuseduentlyclosed.

v QWhen the current output ofthe source 8 exce s r ate Pre e l rfi aed Yh e th current relay 41 closes its contacts 65 and thereby completes acircuit for the control relay 43. This circuit is from one side of thecontrol circuit 31 through the switch 47 the coil of relay 43, contacts65 of relay 41 to the other side of the control circuit 31. Relay 43 byclosing its contacts 66 completes a circuit in parallel around thecontacts 65 of relay 41 so that the relay 43 remains energized in casethe relay 41 should subsequently open its contacts 65. The relay 43 byopening its contacts 58 effects the deenergization of the closing coil38 of the switch 4 it both of the field switches 24 and 25 are.closcd'at this time. The vdeenergization of the closing coil 38 of theswitch 4'causes the switch 4 to open and disconnect the load circuitlfrom the main bus 3. If the voltage across the auxiliary bus 6 is abovea predetermined. value so that the contacts 67 of the voltage relay 45are ,1

age relay 45 to the other side of the control circuit 31, As soon as theswitch 4 opens and the relay'44isenerg1zed a circuit is com.-

pleted through the contacts 70 of the relay 44 for the closing coil 46of the switch 7. This circuit is from one side of the control circuit 31through the switch 47 closing coil 46 of switchi, contacts 70 ofjrelay44, auxiliary contacts 71 of switch 41to the-other side of the controlcircuit31 The energiza- ,t-ion ofthe closing coil 46 effects the closingof .theswitch 7 so that the load circuit 1 is connected to the auxiliarybus 6. Each. of the load circuits is nowindependently energized byaseparate source of current.

Switch 7 by closing its auxiliary contacts 72 completes a lockingcircuit for the control relay 44 which is independent of contacts 68 ofrelay43 and contacts 67 015 relay 45.;

i If at any time. the source connected to the main bus 3 becomesdeenergized so that the voltagerelay 28 opens its contacts 50 and closesits contacts 74, shunt-circuits are completedjaround the coils ofthecontrol relays 3O and37 othat the openingofthe switches 4 and 5 iseffected. The shunt circuit around the coil 30 includes the contacts 74of the relay 28 and the auxiliary contacts 75 of the switch 5, The shuntcircuit around the coil of the relay includes the contacts 7404? therelay28 andthe: auxiliary contacts 75 on the switch 4; Therefore,whenever the source connected tether rnainbus fails both of the loadcircuits are disconnected from the main bus v; In a similar manner itthe source connectedtothe auxiliary bus 6 fails while the switch. 7 isclosed the opening of the switch 7 is efiectedso as to disconnect theload c'ir: ei irelm t e au i us hi result rent output of whicheversourceis connected to said one of said buses and the excitation of thegenerators of both motor generator sets for effecting the disconnectionof certain of said load circuits from said one of said buses, and meansdependent upon predetermined energization of said other bus and thedisconnection of said certain of said load circuits from said one ofsaid buses for effecting the connection of said certain of 1 said loadcircuits to said other bus.

In Witness whereof I have hereunto set my hand this 23rd day of April,1928.

RALSTON E. BEAR.

